Name: reactivation of demembranated cell models in chlamydomonas reinhardtii
Uploaded: 2022-05-06T15:00:00
Description: Watch this Scientific Journal Video about Reactivation of Demembranated Cell Models in Chlamydomonas reinhardtii at JoVE.com

This study was supported by grants from the Japan Society for the Promotion of Science KAKENHI (https://www.jsps.go.jp/english/index.html) to N.U. (19K23758, 21K06295) and K.W. (19H03242, 20K21420, 21H00420), from the Ohsumi Frontier Science Foundation (https://www.ofsf.or.jp/en/) to K.W., and from the Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials (http://alliance.tagen.tohoku.ac.jp/english/) to N.U. and K.W. We thank Ms.&#160;Miyuki Shinohara (Hosei Univ.) for her help in preparing the figures.

A wild-type strain of Chlamydomonas reinhardtii, CC-125, was used for the present study. CC-125 was obtained from Chlamydomonas Resource Center (see Table of Materials) and maintained on a Tris-acetate-phosphate (TAP)16, 1.5% agarose medium at 20-25 &#176;C.
1. Cell culture
<ol>
	<li>Culture Chlamydomonas reinhardtii (CC-125) in TAP medium16 in a 12 h/12 h light-dark period (light conditions f...

<ol>
	<li>Szent-Gyorgyi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Free-energy+relations+and+contraction+of+actomyosin.">Free-energy relations and contraction of actomyosin.</a> Biological Bulletin. 96 (2), 140-161 (1949).</li><li>Hoffman-Berling, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adenosintriphosphat+als+betriebsstoff+von+zellbewegungen.">Adenosintriphosphat als betriebsstoff von zellbewegungen.</a> Biochimica et Biophysica Acta. 14, 182-194 (1954).</li><li>Naitoh, Y., Kaneko, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reactivated+Triton-extracted+models+of+Paramecium:+modification+of+ciliary+movement+by+calcium+ions.">Reactivated Triton-extracted models of Paramecium: modification of ciliary movement by calcium ions.</a> Science. 176 (4034), 523-524 (1972).</li><li>Witman, G. B., Plummer, J., Sander, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chlamydomonas+flagellar+mutants+lacking+radial+spokes+and+central+tubules.+Structure,+composition,+and+function+of+specific+axonemal+components.">Chlamydomonas flagellar mutants lacking radial spokes and central tubules. Structure, composition, and function of specific axonemal components.</a> Journal of Cell Biology. 76 (3), 729-747 (1978).</li><li>R&#252;ffer, U., Nultsch, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flagellar+coordination+in+Chlamydomonas+cells+held+on+micropipettes.">Flagellar coordination in Chlamydomonas cells held on micropipettes.</a> Cell Motility and the Cytoskeleton. 41 (4), 297-307 (1998).</li><li>Sale, W. S., Satir, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direction+of+active+sliding+of+microtubules+in+Tetrahymena+cilia.">Direction of active sliding of microtubules in Tetrahymena cilia.</a> Proceedings of the National Academy of Sciences of the United States of America. 74 (5), 2045-2049 (1977).</li><li>Fox, L. A., Sale, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direction+of+force+generated+by+the+inner+row+of+dynein+arms+on+flagellar+microtubules.">Direction of force generated by the inner row of dynein arms on flagellar microtubules.</a> Journal of Cell Biology. 105 (4), 1781-1787 (1987).</li><li>Kamiya, R., Yagi, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+diversity+of+axonemal+dyneins+as+assessed+by+in+vitro+and+in+vivo+motility+assays+of+Chlamydomonas+mutants.">Functional diversity of axonemal dyneins as assessed by in vitro and in vivo motility assays of Chlamydomonas mutants.</a> Zoolog Science. 31 (10), 633-644 (2014).</li><li>Kamiya, R., Witman, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Submicromolar+levels+of+calcium+control+the+balance+of+beating+between+the+two+flagella+in+demembranated+models+of+Chlamydomonas.">Submicromolar levels of calcium control the balance of beating between the two flagella in demembranated models of Chlamydomonas.</a> Journal of Cell Biology. 98 (1), 97-107 (1984).</li><li>Okita, N., Isogai, N., Hirono, M., Kamiya, R., Yoshimura, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phototactic+activity+in+Chlamydomonas+'non-phototactic'+mutants+deficient+in+Ca2+-dependent+control+of+flagellar+dominance+or+in+inner-arm+dynein.">Phototactic activity in Chlamydomonas 'non-phototactic' mutants deficient in Ca2+-dependent control of flagellar dominance or in inner-arm dynein.</a> Journal of Cell Science. 118, 529-537 (2005).</li><li>Hyams, J. S., Borisy, G. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolated+flagellar+apparatus+of+Chlamydomonas:+characterization+of+forward+swimming+and+alteration+of+waveform+and+reversal+of+motion+by+calcium+ions+in+vitro.">Isolated flagellar apparatus of Chlamydomonas: characterization of forward swimming and alteration of waveform and reversal of motion by calcium ions in vitro.</a> Journal of Cell Science. 33, 235-253 (1978).</li><li>Fujiu, K., Nakayama, Y., Yanagisawa, A., Sokabe, M., Yoshimura, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chlamydomonas+CAV2+encodes+a+voltage-+dependent+calcium+channel+required+for+the+flagellar+waveform+conversion.">Chlamydomonas CAV2 encodes a voltage- dependent calcium channel required for the flagellar waveform conversion.</a> Current Biology. 19 (2), 133-139 (2009).</li><li>Bessen, M., Fay, R. B., Witman, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium+control+of+waveform+in+isolated+flagellar+axonemes+of+Chlamydomonas.">Calcium control of waveform in isolated flagellar axonemes of Chlamydomonas.</a> Journal of Cell Biology. 86 (2), 446-455 (1980).</li><li>Wakabayashi, K., King, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulation+of+Chlamydomonas+reinhardtii+flagellar+motility+by+redox+poise.">Modulation of Chlamydomonas reinhardtii flagellar motility by redox poise.</a> Journal of Cell Biology. 173 (5), 743-754 (2006).</li><li>Saegusa, Y., Yoshimura, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=cAMP+controls+the+balance+of+the+propulsive+forces+generated+by+the+two+flagella+of+Chlamydomonas.">cAMP controls the balance of the propulsive forces generated by the two flagella of Chlamydomonas.</a> Cytoskeleton. 72 (8), 412-421 (2015).</li><li>Gorman, D. S., Levine, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cytochrome+f+and+plastocyanin:+their+sequence+in+the+photosynthetic+electron+transport+chain+of+Chlamydomonas+reinhardi.">Cytochrome f and plastocyanin: their sequence in the photosynthetic electron transport chain of Chlamydomonas reinhardi.</a> Proceedings of the National Academy of Sciences of the United States of America. 54 (6), 1665-1669 (1965).</li><li>Takano, W., Hisabori, T., Wakabayashi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+estimation+of+cytosolic+ATP+concentration+from+the+ciliary+beating+frequency+in+the+green+alga+Chlamydomonas+reinhardtii.">Rapid estimation of cytosolic ATP concentration from the ciliary beating frequency in the green alga Chlamydomonas reinhardtii.</a> Journal of Biological Chemistry. 296, 100156 (2021).</li><li>Wakabayashi, K., Yagi, T., Kamiya, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ca2+-dependent+waveform+conversion+in+the+flagellar+axoneme+of+Chlamydomonas+mutants+lacking+the+central-pair/radial+spoke+system.">Ca2+-dependent waveform conversion in the flagellar axoneme of Chlamydomonas mutants lacking the central-pair/radial spoke system.</a> Cell Motility and the Cytoskeleton. 38 (1), 22-28 (1997).</li><li>Yueh, Y. G., Crain, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deflagellation+of+Chlamydomonas+reinhardtii+follows+a+rapid+transitory+accumulation+of+inositol+1,4,5-trisphosphate+and+requires+Ca2++entry.">Deflagellation of Chlamydomonas reinhardtii follows a rapid transitory accumulation of inositol 1,4,5-trisphosphate and requires Ca2+ entry.</a> Journal of Cell Biology. 123 (4), 869-875 (1993).</li><li>Wakabayashi, K., Ide, T., Kamiya, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium-dependent+flagellar+motility+activation+in+Chlamydomonas+reinhardtii+in+response+to+mechanical+agitation.">Calcium-dependent flagellar motility activation in Chlamydomonas reinhardtii in response to mechanical agitation.</a> Cell Motility and the Cytoskeleton. 66 (9), 736-742 (2009).</li><li>Ueki, N., Wakabayashi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detergent-extracted+Volvox+model+exhibits+an+anterior-posterior+gradient+in+flagellar+Ca2.">Detergent-extracted Volvox model exhibits an anterior-posterior gradient in flagellar Ca2.</a> Proceedings of the National Academy of Sciences of the United States of America. 115 (5), 1061-1068 (2018).</li><li>Tanno, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+four-celled+Volvocales+green+alga+Tetrabaena+socialis+exhibits+weak+photobehavior+and+high-photoprotection+ability.">The four-celled Volvocales green alga Tetrabaena socialis exhibits weak photobehavior and high-photoprotection ability.</a> PLoS One. 16 (10), 0259138 (2021).</li></ol>

There are two critical steps in this protocol. The first is a process known as demembranation, which needs to be carried out gently but thoroughly. Deciliation (i.e., detaching of cilia from the cell body) is induced by vigorous pipetting or vortexing, rendering the cell models immobile even after the addition of ATP. Typically, 5 &#215; 107 cells are suspended in ~0.5 mL of demembranation buffer (final cell density: 1 &#215; 108 cells/mL). The reactivation rate of the cell models would decrease if ...

The in vitro reactivation of demembranated motile cells is a valuable tool for studying the molecular basis for the regulatory mechanism of cell motility. Szent-Gy&#246;rgyi first demonstrated in vitro contraction of rabbit skeletal muscle fibers extracted with 50% glycerol by adding adenosine triphosphate (ATP)1. This experiment was the first to prove that ATP energizes muscle contraction. The methodology was soon applied to the study of ATP-energized ciliary/flagellar motility, such as sperm flagella2, Paramecium cilia3, and Chlamydomonas reinhardtii cilia (also called flagella)4 using non-ionic detergents for demembranation.
The unicellular green alga C. reinhardtii is a model organism for studying cilia: it swims with two cilia by beating them like a human&#39;s breaststroke5. Ciliary motion is driven by dynein, a minus-end directed microtubule-based motor protein6,7. Ciliary dyneins can be classified into outer-arm dyneins and inner-arm dyneins. Mutants lacking each kind of dynein have been isolated as slow-swimming mutants with different motility abnormalities. Detailed in vitro motility analysis of these mutants has significantly advanced dynein research8.
Many important findings have been achieved utilizing this method and its derivatives since the in vitro reactivation experiment of demembranated C. reinhardtii cells (cell models) was established. Reactivation of cell models in a series of Ca2+ buffers, for example, showed9 that two cilia are differently regulated by submicromolar Ca2+, and this asymmetrical cilia control enables the phototactic orientation of C. reinhardtii10. Furthermore, both cilia show waveform conversion from the forward swimming mode (called asymmetric waveform) to the backward swimming mode (called symmetric waveform that appears for a short period when cells are photo- or mechano-shocked)11,12. This waveform conversion is regulated by submillimolar Ca2+, which was shown by the reactivation of the so-called nucleoflagellar apparatus (a complex containing two cilia, the basal bodies, the structures linking the basal bodies with the nucleus, and the remnant of the nucleus)11 or demembranated axonemes of isolated cilia13. Other than Ca2+, redox (reduction-oxidation) poise is a signal that regulates the ciliary beating frequency, which was shown by reactivation of cell models in redox buffers containing different ratios of reduced glutathione vs. oxidized glutathione14. In addition, cyclic adenosine monophosphate (cAMP) asymmetrically regulates two cilia, which was shown by the reactivation of axonemes with photocleavable caged cAMP15. These in vitro findings, combined with genetic findings, have led to a deeper understanding of the molecular mechanisms of cilia regulation in C. reinhardtii.
A protocol for reactivating the cell models is described here. The method is simple, allows for various modifications, and can be applied to multiple organisms that move with cilia. However, because demembranated cells are fragile, it requires some tips to reactivate the motility of cell models with good efficiency while preventing deciliation.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.5 mL plastic tube</td>
			<td>QSP</td>
			<td>502-PLN-Q</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL conical tube</td>
			<td>SARSTEDT</td>
			<td>62.554.502</td>
			<td></td>
		</tr>
		<tr>
			<td>Adenosine 5&#39;-triphosphate disodium salt hydrate (ATP)</td>
			<td>Sima-Aldrich</td>
			<td>A2383</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>KUBOTA</td>
			<td>2800</td>
			<td></td>
		</tr>
		<tr>
			<td>Chlamydomonas strain CC-125</td>
			<td>Chlamydomonas Resource Center</td>
			<td></td>
			<td>https://www.chlamycollection.org/</td>
		</tr>
		<tr>
			<td>Creatine kinase</td>
			<td>Merck</td>
			<td>CK-RO</td>
			<td></td>
		</tr>
		<tr>
			<td>Creatine phosphate</td>
			<td>Merck</td>
			<td>CRPHO-RO</td>
			<td></td>
		</tr>
		<tr>
			<td>Dithiothreitol (DTT)</td>
			<td>Nakalai tesque</td>
			<td>14128-46</td>
			<td></td>
		</tr>
		<tr>
			<td>GEDTA(EGTA)</td>
			<td>Dojindo</td>
			<td>G002</td>
			<td></td>
		</tr>
		<tr>
			<td>Hepes</td>
			<td>Dojindo</td>
			<td>GB70</td>
			<td></td>
		</tr>
		<tr>
			<td>Igepal CA-630</td>
			<td>Sigma-Aldrich</td>
			<td>I8896</td>
			<td>IUPAC name is octylphenoxypolyethoxyethanol: IGEPAL CA-630 is a substitute for Nonidet P-40 (NP-40); NP-40 is no longer available in Sigma-Aldrich.</td>
		</tr>
		<tr>
			<td>MgSO4-7H2O</td>
			<td>Nakalai tesque</td>
			<td>21002-85</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Olympus</td>
			<td>BX-53</td>
			<td></td>
		</tr>
		<tr>
			<td>Pasteur pipette</td>
			<td>fisher scientific</td>
			<td>13-678-20C</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyethylene glycol, Mr 20,000</td>
			<td>Merck</td>
			<td>8.18897.1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Pottasium acetate</td>
			<td>Nakalai tesque</td>
			<td>28434-25</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Hydroxide</td>
			<td>Nacalai</td>
			<td>31511-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>FUJIFILM Wako Pure Chemical Corporation</td>
			<td>196-00015</td>
			<td></td>
		</tr>
	</tbody>
</table>

reactivation of demembranated cell models in chlamydomonas reinhardtii

Since the historical experiment on the contraction of glycerinated muscle by adding ATP, which Szent-Gy&#246;rgyi demonstrated in the mid-20th century, in vitro reactivation of demembranated cells has been a traditional and potent way to examine cell motility. The fundamental advantage of this experimental method is that the composition of the reactivation solution may be easily changed. For example, a high-Ca2+ concentration environment that occurs only temporarily due to membrane excitation in vivo can be replicated in the lab. Eukaryotic cilia (a.k.a. flagella) are elaborate motility machinery whose regulatory mechanisms are still to be clarified. The unicellular green alga Chlamydomonas reinhardtii is an excellent model organism in the research field of cilia. The reactivation experiments using demembranated cell models of C. reinhardtii and their derivatives, such as demembranated axonemes of isolated cilia, have significantly contributed to understanding the molecular mechanisms of ciliary motility. Those experiments clarified that ATP energizes ciliary motility and that various cellular signals, including Ca2+, cAMP, and reactive oxygen species, modulate ciliary movements. The precise method for demembranation of C. reinhardtii cells and reactivation of the cell models is described here.

The demembranation and reactivation process in C. reinhardtii wild type strain (CC-125) is shown here. The culture 2 days after inoculation became a light green color (step 1.1) (Figure 1). Cells were collected (step 2.1), washed (step 2.2), and demembranated (step 2.5).&#160;After demembranation, all cell models became immotile (step 2.7). The demembranated cilia (called axonemes) remain attached to the cell body, which shows that the immotility of the cell models is not caused by ...

Watch this Scientific Journal Video about Reactivation of Demembranated Cell Models in Chlamydomonas reinhardtii at JoVE.com

Reactivation of Demembranated Cell Models in Chlamydomonas reinhardtii

The in vitro reactivation of motile cells is a crucial experiment in understanding the mechanisms of cell motility. The protocol describes reactivating the demembranated cell models of Chlamydomonas reinhardtii, a model organism to study cilia/flagella.

Reactivation of Demembranated Cell Models in Chlamydomonas reinhardtii

Since the historical experiment on the contraction of glycerinated muscle by adding ATP, which Szent-Gy&#246;rgyi demonstrated in the mid-20th century, in ...

This method can help to understand which factors affect cilia motility. The main advantage of this technique is that the phenomena that occur only temporarily in vivo, such inversion of calcium ion concentrations in cilia can be continuously observed in vitro. This method contributes specifically to the research field of motile cilia.It would be difficult for beginners to perform the demembranation step. Hence, it is highly recommended to carry out the steps gently but precisely. Begin by centrifuging approximately 10 milliliters of Chlamydomonas reinhardtii culture at 1, 000 RCF at 20 degrees Celsius for three minutes.Decant the supernatant and aspirate the remnant by a Pasteur pipette. Resuspend the precipitates in approximately five milliliters of washing buffer. Centrifuge cells in the washing buffer at 1, 000 RCF for three minutes at 20 degrees Celsius.Discard the supernatant carefully with a pipette. Add approximately 0.5 milliliters of demembranation buffer to the cell pellet. Shake the tube gently to roughly suspend the cells in the buffer, then put the tube on ice.Suspend the remaining cell pellet gently with a pipette and place the tube on the ice again. Take 5 to 10 microliters of the cell model, dilute tenfold with the dilution buffer, and observe under the microscope to confirm all the cell models are demembranated and not swimming. In a 0.5-milliliter tube, mix 80 microliters of reactivation solution, 10 microliters of ATP solution, and 10 microliters of cell models by tapping the tube.Put approximately 30 microliters of the mixed solution onto a glass slide and gently place a cover slip on it with spacers to avoid a mechanical shock to the cell model. Observe the reactivated cell models under a microscope. After demembranation of the C.reinhardtii culture, all cell models became immotile and the demembranated cilia remained attached to the cell body, confirming that the immotility of the cell models was not caused by de-ciliation.After mixing the cell models with the reactivation buffer in ATP, more than 50%of cell models became motile. Even without the ATP regeneration system, the reactivated cells continued to move for approximately 90 minutes with a final ATP concentration of one millimolar before gradually stopping. The demembranation step is critical.All the cells should stop swimming, but they should not be mixed so strongly that de-ciliation occurs. Researchers can modify this protocol to include reagents such as calcium ions or cyclic AMP, or perform experiments with a mutant lacking a particular protein to identify their biological role.

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Biology

Mating and Tetrad Separation of Chlamydomonas reinhardtii for Genetic Analysis

The unicellular green alga Chlamydomonas reinhardtii (Chlamydomonas) has become a popular organism for research in diverse areas of cell biology and genetics because of its simple life cycle, ease of growth and manipulation for genetic analysis, genomic resources, and transformability of the nucleus and both organelles. Mating strains is a common practice when genetic approaches are used in Chlamydomonass, to create vegetative diploids for analysis of dominance, or following tetrad dissection to ascertain nuclear vs. organellar inheritance, to test allelism, to analyze epistasy, or to generate populations for the purpose of map-based cloning. Additionally, genetic crosses are routinely used to combine organellar genotypes with particular nuclear genotypes. Here we demonstrate standard methods for gametogenesis, mating, zygote germination and tetrad separation. This protocol consists of an easy-to-follow series of steps that will make genetic approaches amenable to scientists who are less familiar with Chlamydomonas. Key parameters and trouble spots are explained. Finally, resources for further information and alternative methods are provided.

Mating and Tetrad Separation of Chlamydomonas reinhardtii for Genetic Analysis

Mating and tetrad separation are required for genetic analysis in Chlamydomonas reinhardtii. Here we demonstrate standard methods for gametogenesis, mating, zygote germination and tetrad dissection. This protocol consists of an easy-to-follow series of steps that will make genetic approaches amenable to scientists who are less familiar with Chlamydomonas.

The unicellular green alga Chlamydomonas reinhardtii (Chlamydomonas) has become a popular organism for research in diverse areas of cell biology and ...

Heterotopic and Orthotopic Tracheal Transplantation in Mice used as Models to Study the Development of  Obliterative Airway Disease

Obliterative airway disease (OAD) is the major complication after lung transplantations that limits long term survival (1-7).
To study the pathophysiology, treatment and prevention of OAD, different animal models of tracheal transplantation in rodents have been developed (1-7). Here, we use two established models of trachea transplantation, the heterotopic and orthotopic model and demonstrate their advantages and limitations.
For the heterotopic model, the donor trachea is wrapped into the greater omentum of the recipient, whereas the donor trachea is anastomosed by end-to-end anastomosis in the orthotopic model.
In both models, the development of obliterative lesions histological similar to clinical OAD has been demonstrated (1-7).
This video shows how to perform both, the heterotopic as well as the orthotopic tracheal transplantation technique in mice, and compares the time course of OAD development in both models using histology.

This video shows and compares two experimental models to study the development of obliterative airway disease (OAD) in mice, the heterotopic and orthotopic tracheal transplantation model.

Obliterative airway disease (OAD) is the major complication after lung transplantations that limits long term survival (1-7).
To study the ...

Video Bioinformatics Analysis of Human Embryonic Stem Cell Colony Growth

Because video data are complex and are comprised of many images, mining information from video material is difficult to do without the aid of computer software.  Video bioinformatics is a powerful quantitative approach for extracting spatio-temporal data from video images using computer software to perform dating mining and analysis. In this article, we introduce a video bioinformatics method for quantifying the growth of human embryonic stem cells (hESC) by analyzing time-lapse videos collected in a Nikon BioStation CT incubator equipped with a camera for video imaging. In our experiments, hESC colonies that were attached to Matrigel were filmed for 48 hours in the BioStation CT.  To determine the rate of growth of these colonies, recipes were developed using CL-Quant software which enables users to extract various types of data from video images.  To accurately evaluate colony growth, three recipes were created. The first segmented the image into the colony and background, the second enhanced the image to define colonies throughout the video sequence accurately, and the third measured the number of pixels in the colony over time.  The three recipes were run in sequence on video data collected in a BioStation CT to analyze the rate of growth of individual hESC colonies over 48 hours. To verify the truthfulness of the CL-Quant recipes, the same data were analyzed manually using Adobe Photoshop software. When the data obtained using the CL-Quant recipes and Photoshop were compared, results were virtually identical, indicating the CL-Quant recipes were truthful. The method described here could be applied to any video data to measure growth rates of hESC or other cells that grow in colonies. In addition, other video bioinformatics recipes can be developed in the future for other cell processes such as migration, apoptosis, and cell adhesion.  

Video bioinformatics is the automated processing, analysis, understanding, and data mining of biological spatio-temporal data extracted from microscopic videos. The purpose of this article is to demonstrate a method for measuring human embryonic stem cell colony growth using a video bioinformatics method.

Because video data are complex and are comprised of many images, mining information from video material is difficult to do without the aid of computer ...

Principles of Rodent Surgery for the New Surgeon

For both scientific and animal welfare reasons, training in basic surgical concepts and techniques should be undertaken before ever seeking to perform surgery on a rodent. Students, post-doctoral scholars, and others interested in performing surgery on rodents as part of a research protocol may not have had formal surgical training as part of their required coursework. Surgery itself is a technical skill, and one that will improve with practice. The principles of aseptic technique, however, often remain unexplained or untaught. For most new surgeons, this vital information is presented in piecemeal fashion or learned on the job, neither of which is ideal. It may also make learning how to perform a particular surgery difficult, as the new surgeon is learning both a surgical technique and the principles of asepsis at the same time. This article summarizes and makes recommendations for basic surgical skills and techniques necessary for successful rodent surgery. This article is designed to supplement hands-on training by the user's institution.

Before attempting surgery, a new surgeon should have training in basic surgical techniques and concepts. This article will present basic surgical considerations with an emphasis on rodents.

For both scientific and animal welfare reasons, training in basic surgical concepts and techniques should be undertaken before ever seeking to perform ...

Manual Restraint and Common Compound Administration Routes in Mice and Rats

Being able to safely and effectively restrain mice and rats is an important part of conducting research. Working confidently and humanely with mice and rats requires a basic competency in handling and restraint methods. This article will present the basic principles required to safely handle animals. One-handed, two-handed, and restraint with specially designed restraint objects will be illustrated. Often, another part of the research or testing use of animals is the effective administration of compounds to mice and rats. Although there are a large number of possible administration routes (limited only by the size and organs of the animal), most are not used regularly in research. This video will illustrate several of the more common routes, including intravenous, intramuscular, subcutaneous, and oral gavage. The goal of this article is to expose a viewer unfamiliar with these techniques to basic restraint and substance administration routes. This video does not replace required hands-on training at your facility, but is meant to augment and supplement that training.

Working safely and humanely with research rodents requires a core competency in handling and restraint methods. This article will present the basic principles required to safely handle and effectively administer compounds to mice and rats.

Being able to safely and effectively restrain mice and rats is an important part of conducting research.  Working confidently and humanely with mice and ...

Evaluation of Mammary Gland Development and Function in Mouse Models

The human mammary gland is composed of 15-20 lobes that secrete milk into a branching duct system opening at the nipple. Those lobes are themselves composed of a number of terminal duct lobular units made of secretory alveoli and converging ducts1. In mice, a similar architecture is observed at pregnancy in which ducts and alveoli are interspersed within the connective tissue stroma. The mouse mammary gland epithelium is a tree like system of ducts composed of two layers of cells, an inner layer of luminal cells surrounded by an outer layer of myoepithelial cells denoted by the confines of a basement membrane2. At birth, only a rudimental ductal tree is present, composed of a primary duct and 15-20 branches. Branch elongation and amplification start at the beginning of puberty, around 4 weeks old, under the influence of hormones3,4,5. At 10 weeks, most of the stroma is invaded by a complex system of ducts that will undergo cycles of branching and regression in each estrous cycle until pregnancy2. At the onset of pregnancy, a second phase of development begins, with the proliferation and differentiation of the epithelium to form grape-shaped milk secretory structures called alveoli6,7. Following parturition and throughout lactation, milk is produced by luminal secretory cells and stored within the lumen of alveoli. Oxytocin release, stimulated by a neural reflex induced by suckling of pups, induces synchronized contractions of the myoepithelial cells around the alveoli and along the ducts, allowing milk to be transported through the ducts to the nipple where it becomes available to the pups 8. Mammary gland development, differentiation and function are tightly orchestrated and require, not only interactions between the stroma and the epithelium, but also between myoepithelial and luminal cells within the epithelium9,10,11. Thereby, mutations in many genes implicated in these interactions may impair either ductal elongation during puberty or alveoli formation during early pregnancy, differentiation during late pregnancy and secretory activation leading to lactation12,13. In this article, we describe how to dissect mouse mammary glands and assess their development using whole mounts. We also demonstrate how to evaluate myoepithelial contractions and milk ejection using an ex-vivo oxytocin-based functional assay. The effect of a gene mutation on mammary gland development and function can thus be determined in situ by performing these two techniques in mutant and wild-type control mice.

This method describes how to dissect and assess mammary gland development and function from mice. Excised mammary glands are assessed for the degree of development using whole mount while milk ejection is evaluated using an oxytocin-based myoepithelial cell contraction assay.

The human mammary gland is composed of 15-20 lobes that secrete milk into a branching duct system opening at the nipple. Those lobes are themselves ...

Diagnostic Necropsy and Selected Tissue and Sample Collection in Rats and Mice

There are multiple sample types that may be collected from a euthanized animal in order to help diagnose or discover infectious agents in an animal colony. Proper collection of tissues for further histological processing can impact the quality of testing results. This article describes the conduct of a basic gross examination including identification of heart, liver, lungs, kidneys, and spleen, as well as how to collect those organs. Additionally four of the more difficult tissue/sample collection techniques are demonstrated. Lung collection and perfusion can be particularly challenging as the tissue needs to be properly inflated with a fixative in order for inside of the tissue to fix properly and to enable thorough histologic evaluation. This article demonstrates the step by step technique to remove the lung and inflate it with fixative in order to achieve optimal fixation of the tissue within 24 hours. Brain collection can be similarly challenging as the tissue is soft and easily damaged. This article demonstrates the step by step technique to expose and remove the brain from the skull with minimal damage to the tissue. The mesenteric lymph node is a good sample type in which to detect many common infectious agents as enteric viruses persist longer in the lymph node than they are shed in feces. This article demonstrates the step by step procedure for locating and aseptically removing the mesenteric lymph node. Finally, identification of infectious agents of the respiratory tract may be performed by bacterial culture or PCR testing of nasal and/or bronchial fluid aspirates taken at necropsy. This procedure describes obtaining and preparing the respiratory aspirate sample for bacterial culture and PCR testing.

This article describes the procedures for conducting a basic postmortem examination of a mouse or rat, and the collection of basic organs, as well as more challenging sample types from for histological, microbiological, and PCR evaluation.

There are multiple sample types that may be collected from a euthanized animal in order to help diagnose or discover infectious agents in an animal ...

Biochemical Reconstitution of Steroid Receptor&#x2022;Hsp90 Protein  Complexes and Reactivation of Ligand Binding

Hsp90 is an essential and highly abundant molecular chaperone protein that has been found to regulate more than 150 eukaryotic signaling proteins, including transcription factors (e.g. nuclear receptors, p53) and protein kinases (e.g. Src, Raf, Akt kinase) involved in cell cycling, tumorigenesis, apoptosis, and multiple eukaryotic signaling pathways 1,2. Of these many 'client' proteins for hsp90, the assembly of steroid receptor&bull;hsp90 complexes is the best defined (Figure 1). We present here an adaptable glucocorticoid receptor (GR) immunoprecipitation assay and in vitro GR&bull;hsp90 reconstitution method that may be readily used to probe eukaryotic hsp90 functional activity, hsp90-mediated steroid receptor ligand binding, and molecular chaperone cofactor requirements. For example, this assay can be used to test hsp90 cofactor requirements and the effects of adding exogenous compounds to the reconstitution process. 
The GR has been a particularly useful system for studying hsp90 because the receptor must be bound to hsp90 to have an open ligand binding cleft that is accessible to steroid 3. Endogenous, unliganded GR is present in the cytoplasm of mammalian cells noncovalently bound to hsp90. As found in the endogenous GR&bull;hsp90 heterocomplex, the GR ligand binding cleft is open and capable of binding steroid. If hsp90 dissociates from the GR or if its function is inhibited, the receptor is unable to bind steroid and requires reconstitution of the GR&bull;hsp90 heterocomplex before steroid binding activity is restored 4 . GR can be immunoprecipitated from cell cytosol using a monoclonal antibody, and proteins such as hsp90 complexed to the GR can be assayed by western blot. Steroid binding activity of the immunoprecipitated GR can be determined by incubating the immunopellet with [3H]steroid. 
Previous experiments have shown hsp90-mediated opening of the GR ligand binding cleft requires hsp70, a second molecular chaperone also essential for eukaryotic cell viability. Biochemical activity of hsp90 and hsp70 are catalyzed by co-chaperone proteins Hop, hsp40, and p23 5. A multiprotein chaperone machinery containing hsp90, hsp70, Hop, and hsp40 are endogenously present in eukaryotic cell cytoplasm, and reticulocyte lysate provides a chaperone-rich protein source 6. 
In the method presented, GR is immunoadsorbed from cell cytosol and stripped of the endogenous hsp90/hsp70 chaperone machinery using mild salt conditions. The salt-stripped GR is then incubated with reticulocyte lysate, ATP, and K+, which results in the reconstitution of the GR&bull;hsp90 heterocomplex and reactivation of steroid binding activity 7. This method can be utilized to test the effects of various chaperone cofactors, novel proteins, and experimental hsp90 or GR inhibitors in order to determine their functional significance on hsp90-mediated steroid binding 8-11.

An in vitro method for preparing functional glucocorticoid receptor (GR)&#x2022;hsp90 protein complexes from purified proteins and cellular lysates is described. The method utilizes immunoadsorption of recombinant GR followed by salt-stripping and protein complex reconstitution. The importance of cofactors and buffer conditions are discussed, as are potential method applications.

Hsp90 is an essential and highly abundant molecular chaperone protein that has been found to regulate more than 150 eukaryotic signaling proteins, ...

Mouse Sperm Cryopreservation and Recovery using the I&middot;Cryo Kit

Thousands of new genetically modified (GM) strains of mice have been created since the advent of transgenesis and knockout technologies. Many of these valuable animals exist only as live animals, with no backup plan in case of emergency. Cryopreservation of embryos can provide this backup, but is costly, can be a lengthy procedure, and generally requires a large number of animals for success. Since the discovery that mouse sperm can be successfully cryopreserved with a basic cryoprotective agent (CPA) consisting of 18&#37; raffinose and 3&#37; skim milk, sperm cryopreservation has become an acceptable and cost-effective procedure for archiving, distributing and recovery of these valuable strains.
 Here we demonstrate a newly developed I&bull;Cryo kit for mouse sperm cryopreservation. Sperm from five commonly-used strains of inbred mice were frozen using this kit and then recovered. Higher protection ratios of sperm motility (&gt; 60&#37;) and rapid progressive motility (&gt; 45&#37;) compared to the control (basic CPA) were seen for sperm frozen with this kit in 5 inbred mouse strains. Two cell stage embryo development after IVF with the recovered sperm was improved consistently in all 5 mouse strains examined. Over a 1.5 year period, 49 GM mouse lines were archived by sperm cryopreservation with the I&bull;Cryo kit and later recovered by IVF.

Here we demonstrate the newly developed I&#x2022;Cryo kit for mouse sperm cryopreservation. Two-cell stage embryo development with frozen-thawed sperm was improved consistently in 5 mouse strains with the use of this kit. Over a 1.5 year period, 49 genetically modified mouse lines were archived by sperm cryopreservation with the I&#x2022;Cryo kit and later successfully recovered by IVF.

Thousands of new genetically modified (GM) strains of mice have been created since the advent of transgenesis and knockout technologies.  Many of these ...

Culturing and Applications of Rotating Wall Vessel Bioreactor Derived 3D Epithelial Cell Models

Cells and tissues in the body experience environmental conditions that influence their architecture, intercellular communications, and overall functions. For in vitro cell culture models to accurately mimic the tissue of interest, the growth environment of the culture is a critical aspect to consider. Commonly used conventional cell culture systems propagate epithelial cells on flat two-dimensional (2-D) impermeable surfaces. Although much has been learned from conventional cell culture systems, many findings are not reproducible in human clinical trials or tissue explants, potentially as a result of the lack of a physiologically relevant microenvironment.
Here, we describe a culture system that overcomes many of the culture condition boundaries of 2-D cell cultures, by using the innovative rotating wall vessel (RWV) bioreactor technology. We and others have shown that organotypic RWV-derived models can recapitulate structure, function, and authentic human responses to external stimuli similarly to human explant tissues 1-6. The RWV bioreactor is a suspension culture system that allows for the growth of epithelial cells under low physiological fluid shear conditions. The bioreactors come in two different formats, a high-aspect rotating vessel (HARV) or a slow-turning lateral vessel (STLV), in which they differ by their aeration source. Epithelial cells are added to the bioreactor of choice in combination with porous, collagen-coated microcarrier beads (Figure 1A). The cells utilize the beads as a growth scaffold during the constant free fall in the bioreactor (Figure 1B). The microenvironment provided by the bioreactor allows the cells to form three-dimensional (3-D) aggregates displaying in vivo-like characteristics often not observed under standard 2-D culture conditions (Figure 1D). These characteristics include tight junctions, mucus production, apical/basal orientation, in vivo protein localization, and additional epithelial cell-type specific properties.
The progression from a monolayer of epithelial cells to a fully differentiated 3-D aggregate varies based on cell type1, 7-13. Periodic sampling from the bioreactor allows for monitoring of epithelial aggregate formation, cellular differentiation markers and viability (Figure 1D). Once cellular differentiation and aggregate formation is established, the cells are harvested from the bioreactor, and similar assays performed on 2-D cells can be applied to the 3-D aggregates with a few considerations (Figure 1E-G). In this work, we describe detailed steps of how to culture 3-D epithelial cell aggregates in the RWV bioreactor system and a variety of potential assays and analyses that can be executed with the 3-D aggregates. These analyses include, but are not limited to, structural/morphological analysis (confocal, scanning and transmission electron microscopy), cytokine/chemokine secretion and cell signaling (cytometric bead array and Western blot analysis), gene expression analysis (real-time PCR), toxicological/drug analysis and host-pathogen interactions. The utilization of these assays set the foundation for more in-depth and expansive studies such as metabolomics, transcriptomics, proteomics and other array-based applications. Our goal is to present a non-conventional means of culturing human epithelial cells to produce organotypic 3-D models that recapitulate the human in vivo tissue, in a facile and robust system to be used by researchers with diverse scientific interests.

A rotating cell culture system that allows epithelial cells to grow under physiological conditions resulting in 3-D cellular aggregate formation is described. The aggregates generated display in vivo-like characteristics not observed in conventional culture models and serve as a more accurate organotypic model system for a multitude of scientific investigations.

Cells and tissues in the body experience environmental conditions that influence their architecture, intercellular communications, and overall functions. ...